Direct reduction of copper slag using rubber seed oil as a reductant: Iron recycling and thermokinetics

Abstract

Copper slag has potential economic and environmental benefits and there is a need for further clean utilization. The traditional recovery methods have the disadvantages of high energy consumption and low Fe recovery ratio. A strategy is proposed for the clean and efficient recovery of Fe from copper slag by deep reduction using rubber seed oil as a reductant. The reduction experiments and thermokinetics analysis are conducted to explore the reaction behavior between rubber seed oil and copper slag. The results show that the Fe recovery ratio of the copper slag is 91.85% and the Fe grade is 95.66% under the optimal conditions for roasting reduction. The process of recycling Fe from copper slag produces new secondary waste residue. Secondary waste residue can be used as a partial starting material for the synthesis of glass-ceramics. The reduction reaction mechanism of copper slag is transformed with increasing temperature. Limiting surface reaction (n = 2) is the restrictive step for the direct reduction reaction region and one-dimension diffusion is the restrictive step for the smelting reduction reaction region. The activation energy of the direct reduction reaction region and smelting reduction reaction region are 16.64 kJ/mol and 13.68 kJ/mol, respectively. This research provides an important approach to the clean utilization of copper slag.